1. Field of the Invention
This invention relates to a method and apparatus for displaying items of information, e.g., data or files, organized in a hierarchical structure, the method and apparatus being capable of displaying portions of the hierarchical structure with which the user is concerned, displaying items of user's concern collectively, and displaying classified trees of items adapted to the user's intention.
2. Description of the Prior Art
Since the advent of compact capacious storage devices such as optical disk memories in recent years, the management and search of a vast amount of information have become routine tasks of the office job. For example, the storing, searching and management activities for a large-scale database, which used to be implemented by specialists, are now carried out by means of an office-oriented document filing system that is designed to be run by the user.
In the document filing system, documents and information are treated in a hierarchical structure in terms of key words and/or concepts in many cases. The hierarchical structure is displayed in the form of menu, on which the user selects items sequentially to reach the intended document or information. However, this menu-based search scheme is sometimes deficient in that if the user once steps in a wrong path, the user is obliged to retry the search from the beginning.
A conventional filing system that overcomes the above-mentioned problem by the application of the knowledge base is disclosed in U.S. Pat. No. 4,868,733 entitled "DOCUMENT FILING SYSTEM WITH KNOWLEDGE-BASE NETWORK OF CONCEPT INTERCONNECTED BY GENERIC, SUBSUMPTION AND SUPERCLASS RELATIONS".
Another proposal for displaying and browsing through a tree of concepts, which are stored in the form of hierarchical structure in a knowledge base, is described in Japanese patent publication JP-A-1-140332.
The following explains in brief the manner of knowledge expression in the knowledge base pertinent to the above-mentioned prior art. FIG. 2 is a diagram showing the manner of knowledge expression for the knowledge base, in which each ellipse represents a concept and each arrow represents the relation between two concepts. In the knowledge base, concepts are organized in a hierarchical structure based on the is-a relation and part-whole relation. All concepts in the knowledge base are linked together in is-a relations below the superlative concept "UNIVERSAL" 201. The is-a relation represents a relation "concept X is (a) concepts Y". Seen from a concept, another concept located above it is called a "super-concept" and another concept located below it is called a "sub-concept". A concept that shares a same super-concept with another concept is called an "appositive concept". For example, in the figure, "person" 212 has a super-concept "intellectual entity" 205, has sub-concepts "female" 220 and "Tanaka Yoko" 213, and has an appositive concept "organization" 206.
Some concepts are linked with other concepts in a part-whole relation. The part-whole relation represents a relation "concept X is part of concept Y". In the part-whole relation, a super-concept, i.e., a concept located above another one is called a "whole-concept" and a sub-concept, i.e., a concept located below another one is called a "part-concept". For example, "X-laboratory" 209 is a part-concept of "A-company" 208.
Each concept can have multiple is-a relations and multiple part-whole relations. For example, the "organization" 206 has two super-concepts of "intellectual entity" 205 and "place" 214 in its is-a relation.
In the knowledge base, things are expressed in terms of two concepts and one relation, i.e., binary relation. First, two generic concepts are related in terms of a generic relation. For example, "person" 212 and "nation" 215 are linked by a generic relation "nationality" 218. Next, two specific concepts are linked in terms of a instance relation. In order for two concepts to establish an instance relation, their super-concepts must be linked by a generic relation of the same name. For example, concepts "Tanaka Yoko" 213 and "Japan" 216 are linked by the instance relation "nationality" 219.
By tracing these relations that link concepts stored in the knowledge base, the user can "browse" through the concepts. It has become possible to make access to knowledge by entering a query, as described in the above-mentioned U.S. Pat. No. 4,868,733. For example, such queries as "article #0468 that covers the workstation developed by B-company seated in Tokyo" and "what company published the article that deals with the subject of information retrieval system ?" are entered to the knowledge base to make access to detailed information.
There have been proposed several methods of displaying the "concept network" of knowledge base that is based on the above-mentioned expression, as described in Japanese patent publication JP-A-1-140332 for example. According to the proposed display method, the system initially displays a hierarchical tree headed by the superlative concept "UNIVERSAL". The system includes a function of showing sub-concepts with a depth of m and a number of branches of n specified by the user for one concept existing on the tree, and a function of hiding sub-concepts of one concept. Further included in the system is a function of listing sub-concepts immediately below one concept, allowing the user to select one with a pointing device and showing the selected concept to the displayed hierarchical tree, a function of searching for concepts based on the matching of a partial character string, and a function of displaying super-concepts of one concept.
However, the foregoing prior art methods have the following problems. One problem is that because of a hierarchical tree displayed in one window, when the user intends to hide a sub-concept with the hiding function, the tree expands as the user traces down the tree, making it difficult to grasp the whole tree and find the intended concept. Another problem is that in searching for a sub-concept by way of several intermediate concepts, the user is obliged to repeat the operations in such a manner of displaying sub-concepts located immediately below one concept and selecting one, and displaying sub-concepts located immediately below the selected concept and selecting one, and so on. In this case, if the user takes a wrong path, the hierarchical tree becomes intricate and the search operation has to be retried from the beginning. Still another problem is that although super-concepts seen from one concept up to the superlative concept "UNIVERSAL" can be listed, the user who intends to view appositive concepts of one super-concept needs to select each super-concept and list sub-concepts located immediately below it. On this account, it is difficult for the user to grasp the taxonomic system and find the position of definition of concepts.
It is possible for a knowledge base to preserve queries in the form of macros, as proposed in U.S. patent application Ser. No. 07/430,241 entitled "SYSTEM FOR DISPLAYING CONCEPT NETWORKS". However, since these macro-wise queries are stored in a file different from that used by the knowledge base in display, the user is obliged to reference to the file and open the window again.
The foregoing prior art systems are merely capable of displaying hierarchical trees of hierarchical structures that are defined in terms of the is-a relation, disallowing the display in classified forms adapted to individual users. Although the prior art systems can display the instance relation to one concept in the form of a frame or can list instance relations between one generic concept and its sub-concepts, these systems are merely capable of displaying hierarchical trees of hierarchical structures that have been defined in advance in terms of the is-a relation. On this account, when the user intends to search for companies through the classification based on the seat, for example, the system can possibly offer only a display of companies that are classified based on the industrial category.
Prior art methods for displaying an appropriate window on the display screen through the operation of nodes are as follows.
A publication "Macintosh user's guide for desktop Macintosh computers" published by Apple Japan, Inc. has the following description in the sections "How to use view menu" (p. 120) and "Displaying hierarchy in a folder" (p. 238): "By single-clicking the triangular mark on the left of the folder icon, files or low-order folders below the folder are displayed. (Icons of files are different depending on each application that have created the files.) By double-clicking the folder icon (or clicking it and selecting "open . . . " from the menu, another window is displayed and files or low-order folders below the folder are displayed". Another section "open outward folder" (p. 238) describes: "By selecting the title of window of a folder, high-order folders above the folder are displayed."
A publication "Microsoft Windows Version 3.1 Getting Started with Microsoft Windows For Microsoft Windows Operating System Gateway 2000 Edition" has the following description in the section "File Manager" (pp. 37-43): "Directory names and associated directory icons are displayed in the form of a hierarchical tree. By specifying a directory in the tree, files or sub-directories under that directory are listed. (Icons of files are different depending on each application that have created the files.)"
In the foregoing prior art systems, when the user intends to display items that are always within the scope of one's concern, the user is obliged to trace menus from the superlative concept (node), carry out the character string matching operation, and repeat the same operation in every time. Items of user's concern are scattered among unnecessary items, and the user is obliged to scroll the window or switch the window frequently. Reserved queries and glossaries are displayed in different windows, and the user is obliged to open and close several windows. Items are displayed solely based on the hierarchical structures that are provided for the database (knowledge base), and the user cannot choose the taxonomic system that suits the user's purpose.